i have an 87 mustang 4cly on the guages it sometimes shows up the battery sign and when it does it take like 10 mins for it to die. why would that happen? bad alternator loose belt or a wiring problem?
That light will come on when the alternator is not working.
Reasons could be belt came off, alternator bad or going bad, and sure a wiring problem somewhere could too. I would look for the obvious and then pull alternator and take to auto parts store to have it checked. This will give u a starting point.
If it is the alternator, be sure to charge battery up before starting car. Otherwise your alternator will be put under unneeded stress and may fail prematurely.
Oh yea, a 3g conversion of the alternator would be a plus too.